Description: patch spelling typo(s) in source

--- a/manpages/man1/fst4sim.1.txt
+++ b/manpages/man1/fst4sim.1.txt
@@ -64,7 +64,7 @@ QRA64 sub-mode designator.
 
 *snr*::
 
- Add Guassian noise to simulate SNR in 2500 Hz bandwidth.
+ Add Gaussian noise to simulate SNR in 2500 Hz bandwidth.
 
 *W*::